Positron emission tomography [PET]
Positron emission tomography [PET]
Positron emission tomography is a diagnostic medical imaging technique that produces three dimensional images of the functional processes in the body. Unlike other imaging techniques, PET scans do not show structural details of tissues and organs of the body. Instead, they show certain chemical activities within the organs and tissues. By analyzing this chemical activity, diseases are diagnosed. PET scanning is very useful in detecting neurological diseases, heart disease, many infections, certain types of inflammatory diseases and cancer.
In positron emission tomography, radioactive isotopes, which emit positrons upon decay, are incorporated into metabolically active molecules like glucose and incorporated into the body. Upon decay, the emitted positron annihilates with an electron and a pair of gamma ray photons is released. These photons travel in opposite directions at almost 180o to each other. The detector detects these photons and based on the number of photons detected, the image of the biochemical activities in the tissues under examination.
PET scanning can be used to detect many types of cancers, heart disease, Alzheimer’s disease and other disorders of the brain. Cancer cells use more energy and therefore appear brightly on the PET scan. However, a PET scan can only suggest the presence of cancer and a biopsy has to be performed to confirm its presence. Similarly, PET can also detect mild changes in the activity of the brain. This can be used to diagnose Alzheimer’s disease and other disorders like epilepsy.
Limitations on the use of PET arise from the fact that it is very costly to manufacture the radionuclide tracers that are used in the procedure. Only few universities and large establishments have the infrastructure to manufacture these. Also there is a lot of controversy about the adverse effects of radioactive tracers used in the procedure.
Related pages:
- Medical Imaging
- Electrocardiogram [ECG]
- Electroencephalogram [EEG]
- How does ultrasound work?
- Ultrasound
- Computed tomography [CT Imaging]
- Magnetic resonance imaging [MRI]
- Commonly Used Radionuclides in Nuclear Medicine
